Smartphones are set to become a prime target for criminals according toGoogle's head of Android security.

"The smartphone OS will become a major security target," said Android Security Leader Rich Cannings, speaking at the Usenix Security Symposium. Attackers can already hit millions of victims with a smartphone attack, and soon that number will be even larger. "Personally I think this will become an epiphany to malware authors," he said.

PCs running Windows are the prime target of criminal attacks today, and hackers have generally steered clear of mobile devices. Security experts say that this is because mobile phones haven't traditionally stored a lot of sensitive data, and because there are so many different devices to attack, it's hard to create a single virus that can infect a large number of users.

That may be changing as more and more people start using iPhones, BlackBerries, and - Google hopes - Android-based phones such as the Samsung I7500.

Google was late to market with an iPhone competitor - G1, the first Android system shipped in October 2008 - but the company hopes to make up ground by making its platform more open and appealing to developers. Android uses open-source components, and Google places fewer restrictions on device makers and application developers than Apple.

For example, Apple must first approve any application before it can be featured in the iPhone store. Google applies no such restrictions in its Android Market.

This open approach to security is further reflected in the fact that Cannings was even allowed to talk about Android security in the first place. Mobile-phone makers are traditionally tight-lipped about their security strategies.

Google's openness gives developers more freedom to innovate, but it can also be misused. "We wanted developers to be able to upload their applications without anyone stopping them from doing that," Cannings said. "Unfortunately this opens us up to malware."

Google runs an application honeypot - a computer set up with test versions of Android - to check Android Market programs, but it has also made changes to the way Android's Linux operating system runs applications in order to make things safer. Each application runs within what Cannings calls an "application sandbox," a virtual-machine environment where the program is unable to mess with other programs on the phone.